Surface cleaning apparatus

ABSTRACT

A surface cleaning apparatus comprises a body including a plurality of compartments. An elongate rotating brush arrangement is positioned within and extends across a first compartment. An electric motor is positioned in a second compartment for driving the brush. The motor for the brush can be operated at a plurality of speeds. A feedback loop maintains the selected speed during operation, and the motor will automatically shut off if the brush is unable to rotate.

FIELD OF THE INVENTION

This invention relates to a surface cleaning apparatus, such as for a floor or upholstery, incorporating an elongate rotating brush arrangement and an electric motor for rotating the brush.

BACKGROUND OF THE INVENTION

Sweepers provide a convenient tool for household cleaning applications. Unlike vacuum cleaners, sweepers do not generate suction to collect dirt and particles from a surface. Instead, a sweeper relies on a rotating brush bar for dirt collection. As a result, sweepers require less power than vacuum cleaners, and may be adequately powered using a battery.

Conventional brush drives do not monitor the rotational speed of the brush. The motor operates at a single speed, leading to a single rotational speed for the brush. This leads to less than ideal cleaning, as a given brush speed may not be effective for collecting particles of various sizes and/or densities. Additionally, depending on the type of surface being swept, the rotational speed of the brush can vary as the surface can impede the progress of the brush when the brush contacts the surface.

Another problem encountered when using a surface cleaning device with a rotating brush bar is that the rotating bar can become jammed during operation. When the brush bar stops rotating, the motor can become overloaded and damage the motor. One possible solution to prevent damage to the motor is to provide an interlock to turn off the motor when the brush bar is unable to rotate. The interlock can be implemented in various ways, such as by turning off the motor when the current delivered to the motor exceeds a threshold value. However, this type of interlock can pose problems, as setting the interlock threshold to a level that guarantees safe operation of the motor may also lead to triggering of the interlock under routine operating conditions.

What is needed is a surface cleaning apparatus that can address the various cleaning situations presented due to variations in the types of dirt and particles that need to be collected. The surface cleaning apparatus should have a brush that can be reliably rotated at a given rotational speed. This will allow the user of the surface cleaning apparatus to be able to select the appropriate brush speed for the surface or the type of dirt or particle that needs to be swept. The surface cleaning apparatus should also have an interlock that provides for safe operation of the motor while minimizing unnecessary shutdowns. Additionally, the surface cleaning apparatus should allow for improved operation time and battery lifetime.

SUMMARY OF THE INVENTION

This invention provides a surface cleaning apparatus which overcomes, or at least ameliorates, at least some of the problems of known apparatus.

In an embodiment, the invention provides a surface cleaning apparatus comprising a body having a first compartment and a second compartment. An elongate rotating brush extends across the first compartment, while an electric motor resides in the second compartment. Preferably, a belt connects the motor and rotating brush to allow the motor to drive the brush. The surface cleaning apparatus also includes a sensor for sensing the rotational speed of the rotating brush and a feedback circuit operably connected to said sensor for maintaining the rotational speed of the rotating brush at a desired level. Preferably, the rotational speed of the brush is maintained at a speed corresponding to one of a plurality of discrete speeds.

In another embodiment, the invention provides a surface cleaning apparatus including a body having at least two compartments. An elongate rotating brush extends across the front of the cleaning apparatus within the body. The body also contains an electric motor for driving the brush. Preferably, a belt connects the motor and rotating brush. The surface cleaning apparatus also includes a sensor for measuring the current drawn by said motor to drive said brush as a function of time and an interlock circuit operably connected to the sensor and the motor. In this embodiment, when the measured current during a time period is greater than one of a plurality of threshold values, the interlock circuit prevents operation of the motor.

In addition to the above embodiment the invention provides a method for sweeping a surface. The method can be used with a sweeper having a body, one or more compartments in said body, and a rotating brush. In the method, the brush is rotated at one of a plurality of discrete speeds. The rotational speed of the brush is sensed, and if the rotational speed of the brush is different than the selected speed of the plurality of discrete speeds, the rotational speed is modified.

In still another embodiment, the invention provides a method for sweeping a surface with a sweeper having a body, one or more compartments in said body, a rotating brush, a motor for rotating said brush, and a battery for driving said motor. The current provided by the battery to the motor for rotating the brush is sensed and compared with a plurality of stored composite current-time cutoff values. If the sensed current exceeds a current cutoff value for greater than the corresponding cutoff time value, the motor is stopped.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention and to show more clearly how it may be carried into effect reference will now be made, by way of example, to the accompanying drawings in which:

FIG. 1 is a view of a surface cleaning apparatus according to an embodiment of the invention;

FIG. 2 is a bottom view of a surface cleaning apparatus according to an embodiment of the invention;

FIG. 3 is a side view of a surface cleaning apparatus according to an embodiment of the invention.

FIG. 4 is a simplified block diagram of the operational elements of a surface cleaning apparatus according to an embodiment of the invention.

FIG. 5 is a block diagram providing additional detail regarding the operational elements shown in FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

Brush rotational speed can directly impact the cleaning efficiency of a surface cleaning apparatus. Heavier or denser objects can often be collected more effectively by a cleaning apparatus having a higher rotational speed for the brush. By contrast, lower density objects or particles that have a relatively large surface area may be easier to collect using a cleaning apparatus with a lower rotational speed. The lower rotational speed will generate less air movement, thus reducing the chances that the low density object or particle will be moved away from the brush by air currents rather than being captured by the cleaning apparatus.

This invention provides a sweeper with a brush having an adjustable rotational speed. In various embodiments, the sweeper can be set to one of a plurality of brush rotational speeds. For example, in an embodiment the sweeper can have at least 2 discrete brush rotational speeds, and preferably at least 3 discrete brush rotational speeds. In addition to having a plurality of speeds available for sweeping, the sweeper can achieve and maintain a selected brush rotational speed. Thus, the speed can be reliably set to the value that provides the best sweeping performance.

In an embodiment, the rotational speed of the brush can be selected to be at least one discrete brush rotational speed of from 3000 rpm to 4200 rpm. In another embodiment, the sweeper can operate at a brush rotational speed of at least 3000 rpm, or at least 3100 rpm, or at least 3200 rpm, or at least 3300 rpm, or at least 3400 rpm, or at least 3500 rpm, or at least 3600 rpm, or at least 3700 rpm, or at least 3800 rpm, or at least 3900 rpm, or at least 4000 rpm, or at least 4100 rpm. In another embodiment, the sweeper can operate at a brush rotational speed of 4200 rpm or less, or 4100 rpm or less, or 4000 rpm or less, or 3900 rpm or less, or 3800 rpm or less, or 3700 rpm or less, or 3600 rpm or less, or 3500 rpm or less, or 3400 rpm or less, or 3300 rpm or less, or 3200 rpm or less, or 3100 rpm or less. In still another embodiment, the sweeper can operate at a brush rotational speed of from 3500 rpm to 4000 rpm.

In an embodiment, the rotational speed of the brush can be selected to be at least one discrete brush rotational speed of from 2300 rpm to 3500 rpm. In another embodiment, the sweeper can operate at a brush rotational speed of at least 2300 rpm, or at least 2400 rpm, or at least 2500 rpm, or at least 2600 rpm, or at least 2700 rpm, or at least 2800 rpm, or at least 2900 rpm, or at least 3000 rpm, or at least 3100 rpm, or at least 3200 rpm, or at least 3300 rpm, or at least 3400 rpm. In another embodiment, the sweeper can operate at a brush rotational speed of 3500 rpm or less, or 3400 rpm or less, or 3300 rpm or less, or 3200 rpm or less, or 3100 rpm or less, or 3000 rpm or less, or 2900 rpm or less, or 2800 rpm or less, or 2700 rpm or less, or 2600 rpm or less, or 2500 rpm or less, or 2400 rpm or less. In still another embodiment, the sweeper can operate at a brush rotational speed of from 2500 rpm to 2800 rpm.

In an embodiment, the rotational speed of the brush can be selected to be at least one discrete brush rotational speed of from 1600 rpm to 2800 rpm. In another embodiment, the sweeper can operate at a brush rotational speed of at least 1600 rpm, or at least 1700 rpm, or at least 1800 rpm, or at least 1900 rpm, or at least 2000 rpm, or at least 2100 rpm, or at least 2200 rpm, or at least 2300 rpm, or at least 2400 rpm, or at least 2500 rpm, or at least 2600 rpm, or at least 2700 rpm. In another embodiment, the sweeper can operate at a brush rotational speed of 2800 rpm or less, or 2700 rpm or less, or 2600 rpm or less, or 2500 rpm or less, or 2400 rpm or less, or 2300 rpm or less, or 2200 rpm or less, or 2100 rpm or less, or 2000 rpm or less, or 1900 rpm or less, or 1800 rpm or less, or 1700 rpm or less. In still another embodiment, the sweeper can operate at a brush rotational speed of from 1900 rpm to 2400 rpm.

This invention also provides a surface cleaning apparatus with an automatic shutoff feature that can stop operation of the surface cleaning device based on multiple, independent shutoff threshold values. In an embodiment, the threshold values are a composite of a current value and time the current has exceeded the threshold. These composite thresholds allow for an automatic shutoff feature with greater flexibility. In the case of a larger current spike, it may be desirable to stop operation of the motor in as little time as possible. On the other hand, a smaller current spike may have a low probability of damaging the motor, and thus the motor can be allowed to operate for a longer period of time before shutdown is necessary.

By having multiple stored current/time composite thresholds, the motor can be protected against damage while avoiding unnecessary shutdowns of the surface cleaning device due to less severe spikes in the current. Any number of thresholds can be established, including two thresholds, or three thresholds, or four thresholds, or five or more thresholds. In an embodiment, the current/time composite thresholds are established to shut down the motor when the current is 10 amps or greater for a specified period of time, or 12.5 amps or greater for a specified period of time, or 15 amps or greater for a specified period of time, or 17.5 amps or greater for a specified period of time, or 20 amps or greater for a specified period of time. In an embodiment, the current/time composite thresholds are established to shut down the motor when the current exceeds a specified value for at least 1 second, or at least 750 milliseconds, or at least 500 milliseconds, or at least 250 milliseconds, or at least 100 milliseconds.

Note that these thresholds are not mutually exclusive. If the current is greater than 15 amps for a period of time, that time period will count toward meeting both a 10 amp and a 15 amp threshold requirement for shutting down the motor.

In still another embodiment, the invention provides a surface cleaning apparatus that preserves the operational lifetime of the battery. When recharging of the battery begins, a recharging interlock prevents operation of the surface cleaning device based on the battery state until a sufficient amount of recharging has occurred. This ensures that the battery will be fully or nearly completely charged before the next use. By avoiding incomplete charging of the battery, the lifetime of the battery can be improved.

In an embodiment, a selector is used to select an operating mode for the sweeper, such as charging mode or sweeping mode. In sweeping mode the battery can provide power to the motor. When the selector is set for charging mode, the battery is recharged by a charge adapter and is not available for powering the motor. In an embodiment, when the surface cleaning apparatus is turned off, the charging mode can be selected by connecting the battery to a charge adapter. In another embodiment, once the selector is set for charging mode, the selector will remain in charging mode until the battery has been recharged for a predetermined period of time. This minimum recharging period can be set to any convenient time, such as at least 30 minutes, or at least 1 hour, or a time period from ranging from 1 hour to 24 hours, or a time necessary to recharge the battery from 0% charge to at least 90% (or at least 95% or at least 100%) of a full charge, or another time period based on the charging rate of the battery. In such an embodiment, once charging of the battery has started, the surface cleaning device cannot be operated using the battery as the power source until the battery has been recharged for the predetermined minimum time.

In yet another embodiment, this invention provides a surface cleaning apparatus that cleans more efficiently due to proper selection of the length of the bristles on the rotating brush.

FIG. 1 depicts an embodiment of a surface cleaning apparatus. The embodiment of FIG. 1 includes a body 100, preferably moulded of one or more plastic materials. Body 100 can be composed of one compartment, or body 100 can include 2 or more separate compartments, such as a first and second compartment; a first, second and third compartment; a forward and rear compartment; a forward, intermediate, and rear compartment; or another combination of compartments.

FIG. 2 shows a bottom view of the embodiment shown in FIG. 1. In this embodiment, body 100 contains an electric motor 205 and a rechargeable battery pack 207. The battery pack can be composed of a single battery or multiple batteries. Indicator 127, shown as a light emitting diode in FIG. 1, indicates whether battery pack 207 is in need of charging. To charge the battery pack, the battery pack may either be connected to a main supply whenever the apparatus is not in use or at suitable times when the battery pack has become depleted. In an embodiment, electric motor 205 and a rechargeable battery pack 207 can be housed in a compartment within body 100. For example, FIG. 3 shows an embodiment of a surface cleaning device having a sealed rear compartment 303. In this embodiment, electric motor 205 and rechargeable battery pack 207 are housed in sealed rear compartment 303. Placing the motor and/or the battery in a separate sealed compartment reduces the risk of dust or other contamination from reaching the motor and/or the battery. This should reduce the risk that the motor and/or the battery will be damaged or otherwise have reduced performance due to contamination from the dust being collected by the sweeper. In other embodiments, the motor an rechargeable battery pack can be located at various locations within body 100, such as in the main compartment of the body 100, or in one of two compartments, or in one of three compartments, or in one of many compartments. As an alternative to a rechargeable battery pack, the apparatus can include disposable batteries or a disposable battery pack. In still another embodiment, the surface cleaning apparatus can be powered by connection to a main power source, such as by electrically connecting the apparatus to a standard household alternating current outlet.

In the embodiment shown in FIG. 1, a switch 108 is provided to permit a user to turn the motor on and off as desired. Another switch 104 is provided to permit a user to switch between various discrete rotational speeds for the motor as desired. In an embodiment, switch 104 is configured to raster up and down through the possible speeds. Thus, if the motor speed was initially in the “low” setting, consecutive pushes of switch 104 would result in the following motor speed settings: Low-Medium-High-Medium-Low. In another embodiment, consecutive pushes of switch 104 can result in the following motor speed settings: Low-Medium-High-Low. In still another embodiment, switch 104 is configured to change speeds according to other patterns. Indicators 126 indicate the current speed of the motor. For example, having one of indicators 126 active can indicate a low speed setting, two indicators can indicate medium speed, while all three being on indicates high speed.

Body 100 also houses a rotating brush assembly 111. In an embodiment, rotating brush assembly 111 includes an elongate rotating brush. Preferably, rotating brush assembly 111 is located near the front of body 100 and extends across substantially the entire width of the body. In an embodiment, the rotating brush assembly is provided with two helically arranged rows of bristles. Preferably, the rows are helices that twist in opposite directions and meet substantially midway between the ends of the brush assembly. At the location of rotating brush assembly 111, the bottom body 100 is open to allow the bristles of the brush arrangement to contact a floor, carpet or the like over which the surface cleaning apparatus is to be moved. In embodiments where body 100 includes multiple compartments, rotating brush assembly 111 is preferably located in a first compartment. In the embodiment shown in FIG. 3, rotating brush assembly 111 is located in forward compartment 309. For convenience a front wall 185 of body 100 can be arcuate to allow the brush assembly to be placed as far forward as possible while still having the forward wall surround the brush assembly.

In the embodiment depicted in FIG. 3, the rotating brush assembly 111 is located toward the front of body 100. In such an embodiment, the surface cleaning apparatus preferably includes a rearwardly inclined wall 315 located behind the rotating brush assembly and between the brush assembly and a dust collection volume. The rearwardly inclined wall allows debris, such as dust, dirt and the like, to be propelled up the wall due to rotation of the brush arrangement 111 and away from the opening where the brush arrangement contacts the surface to be cleaned. This reduces the likelihood of dust travelling back toward the brush assembly, even if the body is inclined forward. The wall 315 extends upwardly to about the same height as the top of the rotating brush assembly 111. In various embodiments, wall 315 is angled toward the rear of the body at an angle of from 15 to 20 degrees, such as 16 degrees, 17 degrees, 18 degrees or 19 degrees.

In various embodiments, the length of the bristles is selected to improve the cleaning performance of the sweeper. Preferably, the bristle length is selected so that the bristles contact a surface to be swept. Because the sweeper may be used on tile surfaces, in an embodiment the bristles are long enough to contact the grout between tiles. The grout between tiles can be at a lower elevation than the tile surface. Thus, the bristle should be long enough to reach this lower elevation surface. In an embodiment, the bristle length is at least 1 inch, or at least 1.5 inches, or at least 2 inches, or at least 2.5 inches, or at least 3 inches.

When the sweeper is placed on a level surface, the bristle bar will be at a certain distance from the surface. In various embodiments, this distance may vary from 0.5 inches to 2.5 inches or more. In order to have the bristles contact the surface to be swept, the bristles should be longer than the distance from the bristle bar to the surface. In an embodiment, the bristles are longer than the distance from the bristle bar to the surface by at least 0.05 inches, or at least 0.1 inches, or at least 0.15 inches. In another embodiment, the bristles are longer than the distance from the bristle bar to the surface by 0.2 inches or less, or 0.15 inches or less, or 0.1 inches or less.

In still another embodiment, the length of the bristles is selected to maintain a desired distance between the end of the bristles and a wall separating the brush assembly from the dust or debris collection compartment. If the distance between the bristles and the wall separating the brush assembly from the debris collection compartment is too large, particles may fall down out of the sweeper without being swept into the debris collection compartment. In an embodiment, the bristle length is selected so that the bristles contact the wall separating the brush assembly from the debris collection compartment during rotation of the brush. In another embodiment, during rotation of the brush, the distance between the end of the bristles and the wall separating the brush assembly from the debris collection compartment is 0.1 inches or less, or 0.2 inches or less, or 0.25 inches or less.

In embodiments where body 100 includes separate compartments, a compartment can be included within the surface cleaning apparatus for capturing dirt and particles. Preferably the compartment for capturing dirt and particles is a compartment located behind the rotating brush assembly. In such an embodiment, the motor and/or the battery for the surface cleaning apparatus is sealed off from the dust collection compartment. The motor and/or battery can be sealed off in a rear compartment or in any other convenient location in the body of the surface cleaning apparatus.

The embodiment shown in FIG. 1 includes a removable dust collection compartment 117. Removing the dust collection compartment allows dust and debris to be emptied out of the surface cleaning apparatus. Preferably, the dust collection compartment 117 has a lower wall or bottom, an upper wall or top, side walls to prevent collected dust from travelling to other regions within the body, and at least one wall formed by the outer wall of the body 100. Based on this construction, dust and other debris will accumulate within the compartment 117. In the embodiment shown in FIG. 1, the removable dust collection compartment 117 forms a portion of the top, side, and bottom walls of body 100. In another embodiment, the dust collection compartment is not removable, but at least one wall of body 100 can be removed to allow dust and debris to be emptied out of the dust collection compartment.

Optionally, body 100 can also include a headlight 128. In an embodiment, headlight 128 is composed of three light emitting diodes that are shielded by a plastic cover.

The brush assembly can be operably connected to the motor by any suitable method. For example, the motor can be used to drive a belt connected to the brush assembly. In an embodiment, the belt can be housed in a separate compartment within the body to prevent dust or debris from reaching the motor and/or the battery.

FIG. 1 also depicts the front of a cleaning apparatus according to an embodiment of the invention. Bottom surface 189 of the front wall 185 is at a higher elevation relative to the surface being swept than the bottom surface of the sweeper body. In an embodiment, the higher elevation of bottom surface 189 is achieved by having the side wall of the body near the front wall rise away from the surface to be swept. In an embodiment, in the vicinity of the front wall, the side wall rises away from the surface to be swept at an angle of at least 5 degrees and preferably at least 10 degrees. In other words, the front portion of the side wall and the surface to be swept form an angle of at least 5 degrees and preferably at least 10 degrees. In an embodiment, this angle is 20 degrees or less, preferably 15 degrees or less. In another embodiment the bottom surface 189 of the front wall can also be angled away from the surface to be cleaned. The angle of the bottom surface relative to the surface to be cleaned can be any convenient angle, such as the same angle as the rise angle of the front portion of the side wall described above. In an embodiment, this angle is at least 5 degrees and preferably at least 10 degrees. In an embodiment, this angle is 20 degrees or less, preferably 15 degrees or less.

In embodiments of the surface cleaning apparatus where the bottom surface of the front wall is elevated relative to the bottom surface of the body, the body can be tipped forward to bring the brush arrangement into closer contact with a surface being cleaned. Tipping the body of the cleaning apparatus forward will bring the brush assembly into a position where the bristles of the brush come into contact (or come into closer contact) with the surface to be cleaned. When the body is tipped forward, the bottom surface of the faceplate may also come into contact with the surface to be cleaned. The additional width of the bottom surface of the faceplate provides a larger contact area for the bottom surface, and thus reduces the tendency of the bottom surface to “dig in” when cleaning a soft surface. Instead, the additional width aids the surface cleaning apparatus in being able to slide along a surface to be cleaned when in the tipped forward position.

In another embodiment, the front wall or faceplate of the forward compartment includes a notch or opening. The notch or opening increases the distance between the bottom surface of the front wall and the surface being cleaned in the region of the notch. The notch or opening provides a location on the front wall of the surface cleaning apparatus where larger particles can be admitted for collection. This is of particular value when the surface cleaning apparatus is being tipped forward so that the bottom surface of the front wall is in contact with the floor.

The height of the notch or opening can be any convenient height that allows particles to be collected by the surface cleaning apparatus while the body is being tipped forward. In an embodiment, the height of the opening relative to the bottom surface of the front wall is the same as the distance from the bottom surface of the front wall to the bottom of the surface cleaning apparatus body. For example, if the bottom surface of the front wall is higher in elevation than the surface to be swept by 1 cm (when the body is not tipped forward), the elevation of the bottom surface in the notch relative to the bottom surface of the rest of the front wall would also be 1 cm. This would lead to a total elevation for the bottom surface of the opening of 2 cm relative to a surface to be swept. In another embodiment, the height of the notch relative to the rest of the front wall is from 0.25 cm to 2.0 cm. In still another embodiment, the height of the notch relative to the rest of the front wall is at least 0.25 cm, or at least 0.5 cm, or at least 1.0 cm, or at least 1.5 cm. In yet another embodiment, the height of the notch relative to the rest of the front wall is 2.0 cm or less, or 1.5 cm or less, or 1.0 cm or less, or 0.5 cm or less.

The width of the notch or opening can be of any convenient size, as long as the width is small enough to prevent undue stress on the front wall when the sweeper body is tipped forward to bring the bristles into closer contact with a surface. Thus, the notch or opening can have various widths, as the width of the front wall can be from 3.5 inches to as large as 20 inches. In other embodiments, the width of the front wall can be at least 5 inches, or at least 7.5 inches, or at least 10 inches, or at least 11.5 inches, or at least 13 inches, or at least 14 inches, or at least 15 inches. In an embodiment, the width of the opening is at least 10% of the width of the front wall and preferably at least 15%. In an embodiment, the width of the opening is 40% or less of the width of the front wall and preferably 25% or less. FIG. 1 shows an example of a notch or opening 195 in a front wall 185.

In still another embodiment, an auxiliary rotary brush may be provided at that side of the rotating brush assembly. FIG. 2 depicts an example of an auxiliary rotary brush 212. Such an auxiliary brush is able to sweep debris into the path of the brush arrangement which might otherwise be missed. The auxiliary brush may be driven by any suitable means, such as a friction/clutch drive, gearing from the brush arrangement, or by friction with the surface to be swept, and is suspended from and extends outwardly beyond the body 100. The auxiliary brush may comprise a conical and/or cylindrical body rotatable about an axis which is inclined to the vertical by about 10 degrees so as to extend outwardly beyond the body 100. Bristles protrude radially outwardly from the periphery of the cylindrical body, but need not be perpendicular to the axis of rotation.

In yet another embodiment, the aperture for collecting dust and debris can be increased by moving or removing a portion or all of the front wall of the surface cleaning apparatus. Moving or removing a portion of the front wall exposes more of the rotating brush assembly. This increases the ability of a user to expose a surface to be cleaned to the rotating brush. The portion of the front wall can be a sliding portion, a rotating portion, a detachable portion, or any other type of portion that allows for additional exposure of bristles to a surface to be cleaned.

During operation, a surface cleaning apparatus according to the invention is placed on a surface to be swept. When the motor is turned on, the motor drives the rotating brush assembly. This allows the surface cleaning apparatus to sweep debris or dust up into the body for collection, such as in a dust collection compartment. Suction is not required for proper operation of the device. However, in an alternative embodiment, the surface cleaning apparatus of this invention can also be incorporated into a vacuum cleaner.

When the surface cleaning apparatus is not in use, it can be stored, for example, in a cupboard or the like, hung on a wall, or plugged into a power source in order to recharge the battery.

In another embodiment, this invention provides an improved way for controlling the operation of the power system and the brush in a surface cleaning device. FIG. 4 depicts a simplified block diagram of a control system for a surface cleaning device. To operate the motor 405, current is supplied by battery 407. The amount of current supplied by battery 407 is at least partially controlled by speed compensation module 435, which receives feedback from feedback network 455 regarding the actual speed of the brush during operation via a control module 475, which can be a single integrated circuit chip. The control module also controls indicators 425, which provide a visible output so that a user can determine the current operating mode of the surface cleaning device.

During operation, the feedback network 455 monitors the rotational speed of the brush. This information is passed to the control module 475, which contains stored values for the desired rotational speed of the brush based on the selected settings of the surface cleaning device. The control module 475 passes this information to the speed compensation module 435, which compares the actual rotational speed of the brush with selected rotational speed. If the actual speed differs from the desired, selected speed, the speed compensation module 435 will change the power delivered to the motor 405 (such as by changing the current) so that the actual speed corresponds to the selected speed.

The combination of the feedback network 455, control module 475, and speed compensation module 435 also provides an interlock to prevent overheating of the motor during a brush jam or other event where the brush is unable to rotate or otherwise creates higher loading than expected. During typical operation, the current delivered to the motor will have a value in the range of 0-5 amps. However, if the brush becomes jammed and thus fails to rotate, the speed compensation module will attempt to increase the current delivered to the motor in order to increase the brush speed. If allowed to continue for an extended period of time, this could result in damage to the motor. To prevent this, the current delivered to the motor is also monitored as a function of time. The current level over time is compared to a series of stored current/time composite threshold values. If the current delivered to the motor remains above a threshold current value for longer than the corresponding time threshold value for that current, the speed compensation unit will cut power to the motor.

The embodiment shown in FIG. 4 includes a battery for providing power to the motor. In an alternative embodiment, the motor can be powered by a main power source, such as by connecting the motor to an alternating current source using a standard wall outlet. Other methods for providing power to the motor will be apparent to those of skill in the art.

FIG. 5 depicts another embodiment of a control scheme for a surface cleaning apparatus. In FIG. 5, motor 505 still receives power from battery 507, but a selector module 545 resides between the motor and battery. The selector 545 controls whether battery 507 is in operating mode or in charging mode. When the selector is set for operating mode, the battery can provide power to the motor 505. When the selector is set for charging mode, the battery is recharged by charge adapter 547 and is not available for powering the motor. In an embodiment, when the surface cleaning apparatus is turned off, the charging mode can be selected by connecting the battery 507 to charge adapter 547. In another embodiment, once the selector is set for charging mode, the selector will remain in charging mode until the battery has been recharged for a predetermined period of time. In such an embodiment, once charging of the battery has started, the surface cleaning device cannot be operated using the battery as the power source until the battery has been recharged for the predetermined minimum time.

In the embodiment shown in FIG. 5, battery 507 should supply current to motor 505 at a relatively constant voltage during operation of the motor. Voltage sensor 559 monitors the battery voltage and passes the voltage information to control module 575. If the voltage of battery 507 changes to a value outside of a predetermined range, control module 575 activates battery indicator 528 to indicate a problem with the battery. Battery indicator 528 is preferably a light-emitting diode (LED), although other types of light sources or other indicators may be used. When power is being delivered to the motor during operation, control module 575 also turns on headlights 528, which are also preferably LEDs.

During operation, a user of the surface cleaning device may set the brush speed to a predetermined speed setting. In an embodiment, the brush speed may be selected to be one of three speeds. The speed is selected by the user using speed selector 556. This value is passed on to control module 575, which sends a signal to speed indicator 526 to provide an indication of the selected speed. In an embodiment, speed indicator 526 comprises 3 LED's. The speed can then be indicated by illuminating the LED's in correspondence to the selected speed. The actual speed of the brush (or alternatively the motor) is measured by speed sensor 558. The current being provided to the motor is also measured by current sensor 557. These values are also collected by control module 575.

During operation, control module 575 passes the selected speed value, the measured speed value, and the measured current value to motor drive 535. In an embodiment, motor drive 535 is a proportional-integral-derivative (PID) compensated pulse-width modulated motor drive. The motor drive compares the selected speed value with the measured speed value. If the selected and measured speeds are different, the motor drive changes the speed of motor 505, such as by changing the current delivered to the motor. The motor drive will continue to change the speed of the motor until the selected speed and measured speed values are equal, or equal to within a predefined tolerance.

An exception to the above-described operation is when an excessive current is delivered to the motor. As described above, the measured current value is tracked as a function of time and compared to composite current/time threshold values. If the measured current value exceeds a current threshold for the corresponding time, motor drive 535 cuts the power to motor 505.

Thus the illustrated surface cleaning apparatus of the present invention incorporates an electrically driven brush arrangement that can be reliably set to one of a plurality of rotational speeds. The brush arrangement is not driven by frictional forces between the surface cleaning apparatus and the surface over which it is to be moved. Thus, efficiency of the apparatus is not dependent on the nature of the frictional contact. Further, the apparatus does not rely on suction means to draw the debris into a storage chamber. Thus, efficiency of the apparatus is not dependent on the effectiveness of suction means and the substantial power drain of suction means on the rechargeable battery is avoided. The provision of the motor at the rear of the apparatus eliminates the need for increased height should the motor be positioned over the compartment for collecting dust and the like and also provides effective full width cleaning which would not be possible if the motor was to be positioned within the compartment for collecting debris. In such a position, debris is likely to accumulate around the motor and cause blockages. The illustrated apparatus overcomes this problem by passing the drive means for the brush arrangement at least partly through the debris compartment.

The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof. 

1. A surface cleaning apparatus, comprising: a) a body having a first compartment and a second compartment; b) an elongate brush that can be rotated extending across the first compartment; c) an electric motor in the second compartment, said motor being capable of rotating the brush at a plurality of discrete speeds; d) a belt connecting the motor and the brush; e) a sensor for sensing a rotational speed of the brush; and f) a feedback circuit operably connected to said rotational speed sensor for maintaining the rotational speed of the brush at a speed corresponding to one of the plurality of discrete speeds.
 2. The surface cleaning apparatus of claim 1, further comprising: a sensor for measuring the current drawn by said motor to drive said brush as a function of time; and an interlock circuit operably connected to said current sensor and said motor, wherein when the current drawn over a time period is measured to be greater than one of a plurality of threshold values, the interlock circuit prevents operation of the motor.
 3. The surface cleaning apparatus of claim 1, further comprising: a battery operably connected to the electric motor; and a recharging interlock to prevent operation of the motor based on the battery during a recharging period.
 4. The surface cleaning apparatus of claim 3, wherein the recharging period is from 1 hour to 24 hours.
 5. The apparatus of claim 1, wherein said first compartment is a forward compartment.
 6. The apparatus of claim 5, wherein said first compartment comprises a front wall having a thickness and having a bottom surface at a higher elevation than a bottom surface of said body, wherein said bottom surface of said front wall has a lip of increased thickness relative to said thickness of said front wall.
 7. The apparatus of claim 6, wherein said bottom surface of the front wall is inclined at an angle relative to the plane of the sweeper body.
 8. The apparatus of claim 6, wherein said front wall of said first compartment further comprises an opening for admitting larger particles into said forward compartment.
 9. The apparatus of claim 1, further comprising a wall separating the first compartment from at least one other compartment, wherein the wall is inclined rearwardly.
 10. The apparatus of claim 9, wherein the wall between the first compartment and the at least one other compartment has an angle of inclination of from 15 to 20 degrees.
 11. The apparatus of claim 1, wherein the second compartment comprises a sealing wall that seals off the second compartment from at least one other compartment in the body.
 12. The apparatus of claim 1, wherein the motor is capable of rotating the brush at 3 or more discrete speeds.
 13. The apparatus of claim 12, wherein the motor is capable of rotating the brush at a first discrete speed of from 3500 to 4000 rpm, a second discrete speed of from 2500 to 2800 rpm, and a third discrete speed of from 1900 to 2400 rpm.
 14. The apparatus of claim 1, wherein the feedback circuit comprises a proportional-integral-derivative compensated motor drive.
 15. A method for sweeping a surface, comprising: providing a sweeper comprising: a body; one or more compartments in said body; a brush that can be rotated in one of the compartments; and a motor in a different compartment than the brush for rotating the brush, the method comprising: rotating said brush at one of a plurality of discrete speeds; sensing the rotational speed of the brush; and restoring the rotational speed of the brush to one of the plurality of discrete speeds.
 16. The method of claim 15, further comprising: sensing current provided to the motor for rotating said brush; comparing the sensed current with a plurality of stored composite current-time cutoff values; and stopping said motor when the sensed current exceeds a current cutoff value for a time greater than the corresponding cutoff time value.
 17. The method of claim 15, wherein the motor is capable of rotating the brush at 3 or more discrete speeds.
 18. The apparatus of claim 17, wherein the motor is capable of rotating the brush at a first discrete speed of from 3500 to 4000 rpm, a second discrete speed of from 2500 to 2800 rpm, and a third discrete speed of from 1900 to 2400 rpm.
 19. A surface cleaning apparatus, comprising: a) a body having a first compartment and a second compartment; b) an elongate brush that can be rotated extending across the first compartment; c) an electric motor in the second compartment, said motor being capable of driving the brush at a plurality of discrete speeds; d) a belt connecting the motor and the brush; e) a sensor for measuring current drawn by said motor to drive said brush as a function of time; and f) an interlock circuit operably connected to said current sensor and said motor, wherein when the current drawn over a time period is measured to be greater than one of a plurality of composite threshold values, the interlock circuit prevents operation of the motor.
 20. The surface cleaning apparatus of claim 19, further comprising: a sensor for sensing the rotational speed of the brush; and a feedback circuit operably connected to said rotational speed sensor for maintaining the rotational speed of the brush at a speed corresponding to one of the plurality of discrete speeds.
 21. The surface cleaning apparatus of claim 19, further comprising: a battery operably connected to the electric motor; and a recharging interlock to prevent operation of the motor based on the battery during a recharging period.
 22. The surface cleaning apparatus of claim 21, wherein the recharging period is from 1 hour to 24 hours.
 23. The apparatus of claim 19, wherein the first compartment is a forward compartment.
 24. The apparatus of claim 23, wherein said first compartment comprises a front wall having a thickness and having a bottom surface at a higher elevation than a bottom surface of said body, wherein said bottom surface of said front wall has a lip of increased thickness relative to said thickness of said front wall.
 25. The apparatus of claim 24, wherein said bottom surface of the front wall is inclined at an angle relative to the plane of the sweeper body.
 26. The apparatus of claim 24, wherein said front wall of said first compartment further comprises an opening for admitting larger particles into said forward compartment.
 27. The apparatus of claim 19, further comprising a wall separating the first compartment from at least one other compartment, wherein the wall is inclined rearwardly.
 28. The apparatus of claim 27, wherein the wall between the first compartment and the at least one other compartment has an angle of inclination of from 15 to 20 degrees.
 29. The apparatus of claim 19, wherein the second compartment comprises a sealing wall that seals off the second compartment from at least one other compartment in the body.
 30. The apparatus of claim 19, wherein the composite threshold values are at least 10 amps for 1 second, at least 15 amps for 500 milliseconds, and at least 20 amps for 100 milliseconds.
 31. A method for sweeping a surface, comprising: providing a sweeper comprising a body; one or more compartments in said body; a brush that can be rotated in one of the compartments; and a motor in a different compartment than the brush for rotating said brush, the method comprising: sensing current provided to the motor for rotating said brush; comparing the sensed current with a plurality of stored composite current-time cutoff values; and stopping said motor when the sensed current exceeds a current cutoff value for a time greater than the corresponding cutoff time value.
 32. The method of claim 31, further comprising: rotating said brush at one of a plurality of discrete speeds; sensing the rotational speed of the brush; and restoring the rotational speed of the brush to said one of a plurality of discrete speeds.
 33. The method of claim 31, wherein the composite current-time cutoff values are 10 amps for 1 second, 15 amps for 500 milliseconds, and 20 amps for 100 milliseconds. 